It marked the second time Allen has tripped an opponent in the past month.
In video of the game broadcast, Allen is seen stretching his left foot backward near midcourt as Rathan-Mayes begins to break upcourt behind him in the game's final seconds. Rathan-Mayes runs into Allen's leg and stumbles to the court.
Allen then turns to Rathan-Mayes with outstretched arms, his palms facing upward.
"He wanted to keep playing physical," Allen said, according to the Fayetteville Observer. "So I tried to walk away from it as he was grabbing me. We ended up tangling up and falling."
Allen also tripped a Louisville player in a win over the Cardinals on Feb. 8 and was whistled for a flagrant foul.
Allen, who is on pace to become the ninth player in Duke history to lead the team in scoring and assists, was not called for a foul Thursday.
The sophomore guard led Duke with 18 points. Many of his points came from his drives to the basket.
"It was nothing," Allen said, according to the Fayetteville newspaper.
ACC senior associate commissioner Paul Brazeau, who attended the game, told ESPN on Thursday night that the conference will review the Florida State-Duke game, including the tripping incident.
Asked what jurisdiction the ACC could have to discipline Allen if necessary, Brazeau said schools and conferences can give private or public reprimands and, if warranted, a suspension.
Earlier this season, the American Athletic Conference suspended Memphis' Shaq Goodwin for a subsequent game after he tripped a South Carolina player while Goodwin was on the bench.
Allen, as mild-mannered as he is off the court, is defined by his aggressive and physical play on it.
Allen said he believes other teams try to take him and Brandon Ingram out of their games by getting physical.
"That's how it's been and that's what people think our weaknesses are," Allen said. "So for me and Brandon, we have to be strong and really tough physically and mentally each night, knowing that we are going to get those blows."
No foul was called on either player Thursday, but it is the second time Allen has tripped an opponent.
Allen was called for a flagrant foul 1 against Louisville when officials viewed Allen on the floor tripping the Cardinals' Ray Spalding when he didn't get a call after a missed basket.
Information from ESPN's Andy Katz and The Associated Press was used in this report.